In general, a head lamp module, which emits light in a direction in which a vehicle travels, is provided in the vehicle in order to ensure a visual field when the vehicle travels at night.
In the head lamp module, intense light is emitted from a light source unit that generates a predetermined amount of heat while being supplied with electric power, and the visual field at a front side of the vehicle is ensured using the emitted light.
However, in the head lamp module for a vehicle according to the related art, moisture is inadvertently generated due to a difference in temperature between a high internal temperature in the head lamp module, which is caused by heat generated from the light source unit, and a low external temperature, and the moisture is attached to a transparent light transmitting glass that is provided in front of the light source unit, and as a result, there are problems in that the moisture disperses the emitted light, consumer's sensitive quality deteriorates because of stains that are generated when the moisture flows, and anti-corrosive performance deteriorates due to the moisture.
Meanwhile, Japanese Patent Application Laid-Open No. 2013-161604 discloses an invention for adjusting a size of an opening portion, which communicates the inside and the outside of a lamp housing, so as to easily discharge moisture generated in a lamp housing in which a light source unit is installed, but there is a problem in that watertight performance deteriorates in the lamp housing because foreign substances flow in through the opening portion together with outside air for dehumidification.
In Japanese Patent Application Laid-Open No. 2013-161604, a filter is installed in the opening portion in order to prevent the inflow of the foreign substances, but the moisture in the lamp housing cannot be easily discharged to the outside because of the filter, and as a result, there is a problem in that a specific power source for discharging the moisture is required.
Meanwhile, in general, an inner surface of the lamp housing is coated with an expensive hydrophilic coating agent in order to form a thin water film on the inner surface of the lamp housing so as to prevent moisture from being formed on the inner surface of the lamp housing, but even in this case, there are problems in that water stains are formed because water flows when an excessive amount of moisture is generated, and costs of products are increased because the hydrophilic coating agent is expensive.